U.S. patent application number 11/635558 was filed with the patent office on 2008-01-10 for organophotoreceptor and electrophotographic imaging apparatus including the organophotoreceptor.
This patent application is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to An-kee Lim.
Application Number | 20080008952 11/635558 |
Document ID | / |
Family ID | 38654627 |
Filed Date | 2008-01-10 |
United States Patent
Application |
20080008952 |
Kind Code |
A1 |
Lim; An-kee |
January 10, 2008 |
Organophotoreceptor and electrophotographic imaging apparatus
including the organophotoreceptor
Abstract
An organophotoreceptor and an electrophotographic imaging
apparatus including the organophotoreceptor are provided. The
organophotoreceptor provides an excellent image quality by
preventing an optical fatigue and a thermal fatigue occurring when
repeatedly used. The organophotoreceptor includes a conductive
support, an undercoat comprising a metal oxide and antioxidant
dispersed in a binder, a charge generation layer comprising a
phthalocyanine-based pigment, and a charge transport layer.
Inventors: |
Lim; An-kee; (Gunpo-si,
KR) |
Correspondence
Address: |
ROYLANCE, ABRAMS, BERDO & GOODMAN, L.L.P.
1300 19TH STREET, N.W., SUITE 600
WASHINGTON,
DC
20036
US
|
Assignee: |
Samsung Electronics Co.,
Ltd.
|
Family ID: |
38654627 |
Appl. No.: |
11/635558 |
Filed: |
December 8, 2006 |
Current U.S.
Class: |
430/59.5 ;
430/59.4; 430/59.6; 430/60; 430/970 |
Current CPC
Class: |
G03G 5/0507 20130101;
G03G 5/144 20130101; G03G 5/0564 20130101; G03G 5/0517 20130101;
G03G 5/051 20130101; G03G 5/0696 20130101; G03G 5/047 20130101;
G03G 5/0514 20130101; G03G 5/142 20130101 |
Class at
Publication: |
430/59.5 ;
430/59.4; 430/970; 430/59.6; 430/60 |
International
Class: |
G03G 5/047 20060101
G03G005/047; G03G 5/14 20060101 G03G005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2006 |
KR |
10-2006-0064460 |
Claims
1. An organophotoreceptor comprising: a conductive support; an
undercoat comprising a metal oxide and a first antioxidant
dispersed in a first binder; a charge generation layer comprising a
phthalocyanine-based pigment; and a charge transport layer.
2. The organophotoreceptor of claim 1, wherein the first
antioxidant comprises a phenol-based antioxidant, a phosphite-based
antioxidant, or mixtures thereof.
3. The organophotoreceptor of claim 2, wherein the phenol-based
antioxidant comprises at least one phenol selected from the group
consisting of 2,6-di-tert-butylphenol,
2,6-di-tert-butyl-4-methoxyphenol,
2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4-methoxyphenol,
2,4-dimethyl-6-tert-butylphenol, 2-tert-butylphenol,
3,6-di-tert-butylphenol, 2,4-di-tert-butylphenol,
2,6-di-tert-butyl-4-ethylphenol, 2-tert-butyl-4,6-methylphenol,
2,4,6-tert-butylphenol, 2,6-di-tert-butyl-4-stearylpronate phenol,
.alpha.-tocopherol, .beta.-tocopherol, .gamma.-tocopherol, naphthol
AS, naphthol AS-D, naphthol AS-BO,
4,4'-methylenebis(2,6-di-tert-butylphenol),
4,4'-methylenebis(6-tert-butyl-4-methylphenol),
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
2,2'-methylenebis(4-ethyl-6-tert-butylphenol),
2,2'-ethylenebis(4,6-di-tert-butylphenol),
2,2'-propylenebis(4,6-di-tert-butylphenol),
2,2'-butanebis(4,6-di-tert-butylphenol),
2,2'-ethylenebis(6-tert-butyl-m-crezole),
4,4'-butanebis(6-tert-butyl-m-crezole),
2,2'-butanebis((6-tert-butyl-p-crezole),
2,2'-thiobis((6-tert-butylphenol),
4,4'-thiobis(6-tert-butyl-m-crezole),
4,4'-thiobis(6-tert-o-crezole),
2,2'-thiobis(4-methyl-6-tert-butylphenol),
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-amyl-4-hydroxybenzyl)benzene,
1,3,5-trimethyl-2,4,6-tris(3-tert-butyl-5-methyl-4-hydroxybenzyl)benzene,
2-tert-butyl-5-methyl-phenylaminephenol,
4,4'bisamino(2-tert-butyl-4-methylphenol),
N-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate,
2,2,4-trimethyl-6-hydroxy-7-tert-butylchroman,
tetrakis(methylene-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)methane-
, and 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane.
4. The organophotoreceptor of claim 2, wherein the phosphite-based
antioxidant comprises at least one phosphite selected from the
group consisting of tri(2,4-di-t-butylphenyl)phosphite,
bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,
bis(2,4-di-dicumylphenyl)pentaerythritol diphosphite,
tri(4-n-nonylphenyl)phosphite, and
tetrakis(2,4-di-tert-butyl-phenyl)
4,4'-biphenylene-diphosphite.
5. The organophotoreceptor of claim 1, wherein the amount of the
first antioxidant is in the range of about 0.01-20 parts based on
100 parts by weight of the first binder.
6. The organophotoreceptor of claim 1, wherein the
phthalocyanine-based pigment is a phthalocyanine-based derivative
of Formula 1, a phthalocyanine-based compound of Formula 2, or a
mixture or cocrystal thereof: ##STR00006## where X.sub.1, X.sub.2,
X.sub.3, and X.sub.4 are each independently a substituted or
unsubstituted 2,3-naphthalene ring or a substituted or
unsubstituted benzene ring, and at least one of X.sub.1, X.sub.2,
X.sub.3, and X.sub.4 is a 2,3-naphthalene ring; R.sub.1, R.sub.2,
R.sub.3, and R.sub.4 are each independently a hydrogen atom, a
halogen atom, a nitro group, a substituted or unsubstituted C1-20
alkyl group, or a substituted or unsubstituted C1-20 alkoxy group;
and M.sub.1 is a hydrogen molecule, a halogenated aluminum, or Ti,
V, Zr, Ge, Ga, Sn, Si, or In having an oxygen atom, a halogen atom,
or hydroxyl group bound thereto; and ##STR00007## where M.sub.2 is
a hydrogen molecule, Cu, Fe, Mg, Sn, Pb, Zn, Co, Ni, Mo,
halogenated aluminum, or Ti, V, Zr, Ge, Ga, Sn, Si, or In to which
an oxygen atom, a halogen atom, or a hydroxyl group is bound; and
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11,
R.sub.12, R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17,
R.sub.18, R.sub.19, and R.sub.20 are each independently a hydrogen
atom, a halogen atom, a nitro group, a substituted or unsubstituted
C.sub.1-20 alkyl group, or a substituted or unsubstituted
C.sub.1-20 alkoxy group.
7. The organophotoreceptor of claim 6, wherein, in the mixture or
cocrystal of the phthalocyanine-based derivative of Formula 1 and
the phthalocyanine-based compound of Formula 2, the weight ratio of
the phthalocyanine-based derivative of Formula 1 to the
phthalocyanine-based compound of Formula 2 is in the range of about
0.0001:1-0.5:1.
8. The organophotoreceptor of claim 6, wherein the
phthalocyanine-based pigment is the cocrystal of the
phthalocyanine-based derivative of Formula 1 and the
phthalocyanine-based compound of Formula 2.
9. The organophotoreceptor of claim 8, wherein the cocrystal of the
phthalocyanine-based derivative of Formula 1 and the
phthalocyanine-based compound of Formula 2 has a crystal form of a
.gamma.-type or Y-type oxotitanyl phthalocyanine of which the
sharpest diffraction peak appears at a Bragg angle
(2.theta..+-.0.2.degree.) of 27.1.degree. in an X-ray diffraction
spectrum.
10. The organophotoreceptor of claim 8, wherein the cocrystal of
the phthalocyanine-based derivative of Formula 1 and the
phthalocyanine-based compound of Formula 2 has a crystal form of an
.alpha.-type oxotitanyl phthalocyanine crystal of which the
sharpest diffraction peak appears at a Bragg angle
(2.theta..+-.0.2.degree.) of 7.5.degree. in an X-ray diffraction
spectrum.
11. The organophotoreceptor of claim 8, wherein the cocrystal of
the phthalocyanine-based derivative of Formula 1 and the
phthalocyanine-based compound of Formula 2 has a crystal form of an
X-type nonmetallic phthalocyanine crystal of which sharp
diffraction peaks appear at Bragg angles (2.theta..+-.0.2.degree.)
of 7.5.degree. and 9.2.degree. in an X-ray diffraction
spectrum.
12. The organophotoreceptor of claim 1, wherein the amount of the
phthalocyanine-based pigment is in the range of about 10-100 wt %
based on the total weight of the charge generation layer.
13. The organophotoreceptor of claim 1, wherein the thickness of
the charge generation layer is in the range of about 0.001-10
.mu.m.
14. The organophotoreceptor of claim 1, wherein the metal oxide
comprises at least one oxide selected from the group consisting of
tin oxide, indium oxide, zinc oxide, titan oxide, silicon oxide,
zirconium oxide, and aluminum oxide.
15. The organophotoreceptor of claim 1, wherein the binder
comprises at least one resin selected from the group consisting of
a thermosetting resin, an amino resin, a photosetting resin, a
polyamid resin, a polyurethane resin, and an epoxy resin.
16. The organophotoreceptor of claim 1, wherein the weight ratio of
the metal oxide and the binder is in the range of about
0.1/1-10/1.
17. The organophotoreceptor of claim 1, wherein the thickness of
the undercoat is in the range of about 0.1-20 .mu.m.
18. The organophotoreceptor of claim 1, wherein the charge
transport layer comprises a charge transporting material and a
second binder, wherein the second binder is a Z-type polycarbonate
represented by Formula 3, a BPPC represented by Formula 4, or a
mixture thereof: ##STR00008##
19. The organophotoreceptor of claim 18, wherein the charge
transport layer further comprises a second antioxidant, wherein the
second antioxidant is a phenol-based antioxidant, a phosphite-based
antioxidant, or a mixture thereof.
20. An electrophotographic imaging apparatus comprising the
organophotoreceptor of claim 1.
21. An electrophotographic cartridge that is installed in an
electrophotographic imaging apparatus and is separated from the
electrophotographic imaging apparatus, the electrophotographic
cartridge comprising: the organophotoreceptor of claim 1; and at
least one device selected from the group consisting of a charging
device that charges the organophotoreceptor, a developing device
that develops a electrostatic latent image formed on the
organophotoreceptor, and a cleaning device that cleans the surface
of the organophotoreceptor.
22. An electrophotographic drum comprising: a drum that is
installed in an electrophotographic imaging apparatus and is
separated from the electrophotographic imaging apparatus imaging
apparatus; and the organophotoreceptor of claim 1.
23. An electrophotographic imaging apparatus comprising: a
photoreceptor unit comprising the organophotoreceptor of claim 1; a
charging device that charges the photoreceptor unit; an imagewise
light irradiation device that irradiates an imagewise light to the
photoreceptor unit in order to form a electrostatic latent image on
the photoreceptor unit; a developing unit that develops the
electrostatic latent image using a toner in order to form a toner
image on the photoreceptor unit; and a transferring device that
transfers the toner image onto a receptor.
24. An organophotoreceptor comprising: a conductive support; an
undercoat comprising a metal oxide and a first antioxidant
dispersed in a first binder; a charge generation layer comprising a
phthalocyanine-based pigment, wherein the phthalocyanine-based
pigment is a cocrystal has a crystal form selected from the group
consisting of .gamma.-type or Y-type oxotitanyl phthalocyanine of
which the sharpest diffraction peak appears at a Bragg angle
(2.theta..+-.0.2.degree.) of 27.1.theta. in an X-ray diffraction
spectrum, an .alpha.-type oxotitanyl phthalocyanine crystal of
which the sharpest diffraction peak appears at a Bragg angle
(2.theta..+-.0.2.degree.) of 7.5.degree. in an X-ray diffraction
spectrum, and X-type nonmetallic phthalocyanine crystal of which
sharp diffraction peaks appear at Bragg angles
(2.theta..+-.0.2.degree.) of 7.5.degree. and 9.2.degree. in an
X-ray diffraction spectrum; and a charge transport layer.
25. The organophotoreceptor of claim 24, wherein the
phthalocyanine-based pigment is a phthalocyanine-based derivative
of Formula 1, a phthalocyanine-based compound of Formula 2, or a
mixture or cocrystal thereof: ##STR00009## where X.sub.1, X.sub.2,
X.sub.3, and X.sub.4 are each independently a substituted or
unsubstituted 2,3-naphthalene ring or a substituted or
unsubstituted benzene ring, and at least one of X.sub.1, X.sub.2,
X.sub.3, and X.sub.4 is a 2,3-naphthalene ring; R.sub.1, R.sub.2,
R.sub.3, and R.sub.4 are each independently a hydrogen atom, a
halogen atom, a nitro group, a substituted or unsubstituted C1-20
alkyl group, or a substituted or unsubstituted C1-C20 alkoxy group;
and M.sub.1 is a hydrogen molecule, a halogenated aluminum, or Ti,
V, Zr, Ge, Ga, Sn, Si, or In having an oxygen atom, a halogen atom,
or hydroxyl group bound thereto; and ##STR00010## where M.sub.2 is
a hydrogen molecule, Cu, Fe, Mg, Sn, Pb, Zn, Co, Ni, Mo,
halogenated aluminium, or Ti, V, Zr, Ge, Ga, Sn, Si, or In to which
an oxygen atom, a halogen atom, or a hydroxyl group is bound; and
R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, R.sub.11,
R.sub.12, R.sub.13, R.sub.14, R.sub.15, R.sub.16, R.sub.17,
R.sub.18, R.sub.19, and R.sub.20 are each independently a hydrogen
atom, a halogen atom, a nitro group, a substituted or unsubstituted
C.sub.1-20 alkyl group, or a substituted or unsubstituted
C.sub.1-20 alkoxy group.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims the benefit of Korean Patent
Application No. 10-2006-0064460, filed on Jul. 10, 2006, in the
Korean Intellectual Property Office, the disclosure of which is
hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an organophotoreceptor and
to an electrophotographic imaging apparatus including the
organophotoreceptor. More particularly, the invention relates to an
organophotoreceptor that provides excellent image quality by
preventing optical fatigue and thermal fatigue that normally occurs
when the organophotoreceptor is repeatedly used and an
electrophotographic imaging apparatus including the same.
[0004] 2. Description of the Related Art
[0005] In general, an electrophotographic photoreceptor includes an
alumite layer, a charge generation layer, and a charge transport
layer, which are sequentially deposited on an aluminum drum.
However, more typically an electrophotographic photoreceptor
includes an undercoat, a charge generation layer, and a charge
transport layer sequentially deposited on an aluminum drum. The
alumite layer is expensive to manufacture, and the undercoat is
unstable in an apparatus that includes an electrophotographic
photoreceptor. Organic photoconductive materials such as a
naphthoquinone-based compound, an azo-based compound, an azulenium
salt-based compound, a pyrylium salt-based compound, a
phthalocyanine-based compound, and the like are sensitive to
semiconductor laser light. However, a naphthoquinone-based compound
has low sensitivity, and an azo-based compound cannot be stably
synthesized. In particular, a naphthoquinone-based compound and an
azo-based compound are chemically unstable with respect to strong
light, such as laser light.
[0006] On the other hand, phthalocyanine-based compound are
chemically and physically stable and thus is used as a blue pigment
in a wide range of applications, such as inks and paints, and
charge generating materials for electrophotographic
photoreceptors.
[0007] In general, phthalocyanine-based compounds have different
ultraviolet light and visible light absorption spectra and
electrical properties according to the kind of a central metal in
their molecular structure, and thus have different properties as a
charge generation material for an electrophotographic
photoreceptor. In addition, even when their central metals are the
same, their properties can vary according to crystalline structure
or particle size.
[0008] There are many phthalocyanine-based charge generating
materials, such as copper phthalocyanine, nonmetallic
phthalocyanine, chloro aluminum phthalocyanine, chloro indium
phthalocyanine, chloro galium phthalocyanine, chloro germanium
phthalocyanine, oxobanadyl phthalocyanine, oxotitanyl
phthalocyanine, hydroxy germanium phthalocyanine, hydroxy gallium
phthalocyanine and the like.
[0009] In addition, electrophotographic photoreceptors can be
prepared by coating a composition including a photoconductive
pigment dispersed in a binder resin on a conductive support, by
sequentially depositing a charge generation layer and a charge
transport layer on a conductive support, by sequentially depositing
a charge transport layer and a charge generation layer on a
conductive support, or by coating a charge generating material
dispersed-composition in a charge transport layer on a conductive
support. Electrophotographic photoreceptors having these structures
are susceptible to optical fatigue, have low durability due to heat
generated during repeated use of a device, such as a printer, and
have image aging characteristics due to changes in temperature and
humidity. When a photoreceptor drum that experiences optical
fatigue and deteriorated output, the resulting image obtained
during the development process may have low concentration or
defects. These problems can be solved by using an antioxidant or an
ultraviolet light absorbing agent. However, there is still a need
to develop a proper technique to prevent these problems. In
addition, when an undercoat is prepared by coating a composition
including a metal oxide dispersed in a binder resin on a conductive
support, image aging occurs since the binder resin and the metal
oxide are very susceptible to changes in the environment.
[0010] A phthalocyanine-based charge generating material used as a
charge generating material is manufactured in an aggregated crystal
state of primary particles and has a particle size of a few microns
or more. Accordingly, when the phthalocyanine-based charge
generating material is used to prepare an electrophotographic
photoreceptor, the phthalocyanine-based charge generating material
of an aggregated crystal state is first dispersed using a proper
organic solvent to prepare a dispersion coating solution so that
particulates of the phthalocyanine-based charge generating material
can be obtained. The dispersion coating solution is coated on a
conductive substrate to form a thin film. At this point, when the
charge generating material included in the dispersion coating
solution undergoes crystal transition or crystal growth, or
aggregates to thereby form large particles, electrophotographic
characteristics may deteriorate or the obtained thin film may have
irregular electrical characteristics. In addition, image defects,
such as black spots may occur and image resolution may decrease.
Due to these problems, the charge generating material in the
dispersing solution having stability with respect to crystal
transition, crystal growth or aggregation is required. It is known
that the phthalocyanine-based compound has various crystal forms
and these crystal forms are thermodynamically stable when
synthesized. However, when the phthalocyanine-based compound
undergoes a crystal form transition process to be used for
electrophotographic use, the phthalocyanine-based compound changes
into an unstable crystal form or a semi-stable crystal form. In
particular, in an organic solvent, the phthalocyanine-based
compound is unstable with respect to crystal transition or crystal
growth and aggregation.
[0011] However, there are no phthalocyanine-based charge generating
materials that can overcome these problems as described above. An
oxotitanyl phthalocyanine of a Y-type crystal form has the sharpest
diffraction peak at a Bragg angle 2.theta.(.+-.0.2.degree.) of
27.3.degree. in an X-ray diffraction spectrum and relatively good
sensitivity. Various other crystal forms having different
properties have been suggested. However, this crystal form belongs
to a type II crystal form having poor resistance to solvents. That
is, the oxotitanyl phthalocyanine of a Y-type crystal form itself
has relatively high sensitivity, but is unstable with respect to
solvents (refer to Japanese Patent Laid-open Publication No. Sho
62-67094).
[0012] Since the crystal characteristics age in dispersion coating
solutions of a conventional phthalocyanine-based charge generating
material, the photoreceptor has poor properties such as poor
stability, bad credibility. In addition, the photoreceptor has low
storage stability and thus increased manufacturing costs.
[0013] A conventional phthalocyanine-based charge generating
material has excellent sensitivity when its dispersion coating
solution is prepared. However, crystal properties of the
phthalocyanine-based charge generating material in the coating
solution substantially age and the phthalocyanine-based charge
generating material is very unstable. Therefore, there are many
problems in terms of quality stabilization, manufacturing
properties, and photoreceptor costs.
[0014] Accordingly, there is a need to develop a suppressant that
prevents a change in crystal form of the phthalocyanine-based
charge generating material while electrophotographic properties are
maintained There is also a need for a dispersion stabilizer that
prevents aggregation of crystals, a charge generating material
having high sensitivity that is stable with respect to crystal
growth or crystal aggregation, and a photoreceptor that is suitable
for processing digital signals.
SUMMARY OF THE INVENTION
[0015] The present invention provides an organophotoreceptor having
improved aging characteristics due to an optical fatigue and
thermal fatigue occurring repeated used.
[0016] The present invention also provides an electrophotographic
imaging apparatus including the organophotoreceptor, an
electrophotographic cartridge including the organophotoreceptor,
and an electrophotographic drum including the
organophotoreceptor.
[0017] According to an aspect of the present invention, an
organophotoreceptor is provided that includes a conductive support;
an undercoat comprising a metal oxide and antioxidant dispersed in
a binder; a charge generation layer comprising a
phthalocyanine-based pigment; and a charge transport layer.
[0018] The antioxidant may be a phenol-based antioxidant, a
phosphite-based antioxidant, or a mixture thereof.
[0019] The phthalocyanine-based pigment may be a
phthalocyanine-based derivative of Formula 1, a
phthalocyanine-based compound of Formula 2, or a mixture or
cocrystal thereof:
##STR00001##
where X.sub.1, X.sub.2, X.sub.3, and X.sub.4 are each independently
a substituted or unsubstituted 2,3-naphthalene ring or a
substituted or unsubstituted benzene ring, and at least one of
X.sub.1, X.sub.2, X.sub.3, and X.sub.4 is a 2,3-naphthalene
ring;
[0020] R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each
independently a hydrogen atom, a halogen atom, a nitro group, a
substituted or unsubstituted C.sub.1-20 alkyl group, or a
substituted or unsubstituted C.sub.1-20 alkoxy group; and
[0021] M.sub.1 is a hydrogen molecule, a halogenated aluminum, or
Ti, V, Zr, Ge, Ga, Sn, Si, or In to which an oxygen atom, a halogen
atom, or hydroxyl group is bound;
##STR00002##
where M.sub.2 is a hydrogen molecule, Cu, Fe, Mg, Sn, Pb, Zn, Co,
Ni, Mo, halogenated aluminum, or Ti, V, Zr, Ge, Ga, Sn, Si, or In
to which an oxygen atom, a halogen atom, or a hydroxyl group is
bound; and
[0022] R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10,
R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15, R.sub.16,
R.sub.17, R.sub.18, R.sub.19, and R.sub.20 are each independently a
hydrogen atom, a halogen atom, a nitro group, a substituted or
unsubstituted C.sub.1-20 alkyl group, or a substituted or
unsubstituted C.sub.1-20 alkoxy group.
[0023] According to another aspect of the present invention, an
electrophotographic imaging apparatus is provided that includes the
organophotoreceptor.
[0024] According to another aspect of the present invention, an
electrophotographic cartridge is provided that is installed in an
electrophotographic imaging apparatus and is seperated from the
electrophotographic imaging apparatus, the electrophotographic
cartridge including: an organophotoreceptor including a conductive
support, an undercoat comprising a metal oxide and antioxidant
dispersed in a binder, a charge generation layer comprising a
phthalocyanine-based pigment, and a charge transport layer that
includes a charge transport material; and at least one device
selected from the group consisting of a charging device that
charges the organophotoreceptor, a developing device that develops
a electrostatic latent image formed on the organophotoreceptor, and
a cleaning device that cleans the surface of the
organophotoreceptor.
[0025] According to another aspect of the present invention, an
electrophotographic drum is provided that includes: a drum that is
installed in an electrophotographic imaging apparatus and is
separated from the electrophotographic imaging apparatus imaging
apparatus; and an organophotoreceptor including a conductive
support; an undercoat comprising a metal oxide and antioxidant
dispersed in a binder; a charge generation layer comprising a
phthalocyanine-based pigment; and a charge transport layer
including a charge transporting material and a second antioxidant
dispersed in a second binder.
[0026] According to another aspect of the present invention, an
electrophotographic imaging apparatus is provided that includes: a
photoreceptor unit including a conductive support; an undercoat
comprising a metal oxide and antioxidant dispersed in a binder; a
charge generation layer comprising a phthalocyanine-based pigment;
and a charge transport layer including a charge transporting
material; a charging device that charges the photoreceptor unit; an
imagewise light irradiation device that irradiates an imagewise
light to a photoreceptor unit charged by the charging device in
order to form a electrostatic latent image on the photoreceptor
unit; a developing unit that develops the elastic latent image
using a toner in order to form a toner image on the photoreceptor
unit; and a transferring device that transfers the toner image onto
a receptor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0028] FIG. 1 is a schematic view of an electrophotographic imaging
apparatus including an electrophotographic drum and an
electrophotographic cartridge, according to an embodiment of the
present invention;
[0029] FIG. 2 is an XRD chart of a pigment that has undergone a
crystal form transition treatment according to Preparation Example
2;
[0030] FIG. 3 is an XRD chart of a pigment that has undergone a
crystal form transition treatment according to Preparation Example
3; and
[0031] FIG. 4 is an XRD chart of a pigment that has undergone a
crystal form transition treatment according to Preparation Example
4.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The present invention will now be described more fully with
reference to the accompanying drawings.
[0033] In an electrophotographic organophotoreceptor according to
an embodiment of the present invention, an antioxidant having a
specific structure is used in an undercoat and a charge transport
layer and a phthalocyanine-based pigment is used in a charge
generation layer. The electrophotographic organophotoreceptor
having such features undergoes less optical fatigue and thermal
fatigue due to environmental changes occurring during repeated use.
In addition, when an electrophotographic device, such as a laser
printer, a digital copier, or a facsimile, includes the
electrophotographic organophotoreceptor, image aging
characteristics occurring when used for a long period of time can
improve even when an external environment is dramatically changed
and its durability improves, and thus excellent image properties
can be obtained.
[0034] According to the present invention, a metal oxide used in an
undercoat, a charge generating material, and a charge transporting
material are appropriately combined so that electrophotographic
properties of an organophotoreceptor improves, image defects can be
prevented, print products having high resolution can be obtained.
The electrophotographic organophotoreceptor in which the metal
oxide of the undercoat, the charge generating material, and the
charge transporting material are appropriately combined has high
sensitiveness, excellent charge potential retention properties, low
aging properties, high heat resistance, high durability, and
excellent image properties, and thus has high credibility.
[0035] The organophotoreceptor according to an embodiment of the
present invention is obtained by forming an undercoat, a charge
generation layer, and a charge transport layer on a conductive
support. The conductive support can be formed of a metallic
substance, such as aluminum, aluminum alloy, stainless copper,
copper, or nickel. Alternatively, the conductive support can be an
insulating substrate coated with a conductive film of aluminum,
copper, palladium, tin oxide, or indium oxide. The insulating
substrate can be formed of polyester film, paper, glass and the
like. Meanwhile, a positive electrode oxide film can be formed
using a sulfuric acid solution, oxalic acid, and others between the
conductive support and the charge generation layer, or a binder
layer formed of a polyamide resin, a polyurethane resin, or an
epoxy resin can be coated between the conductive support and the
charge generation layer.
[0036] The undercoat formed on the conductive support used in the
embodiment of the present invention includes a metal oxide and
antioxidant dispersed in a binder. The amount of the antioxidant
may be in the range of about 0.01-20 parts by weight based on 100
parts by weight of the binder. When the amount of the antioxidant
is less than 0.01 parts by weight, the occurrence of the image
aging is less suppressed. On the other hand, when the amount of the
antioxidant is more than 20 parts by weight, an image may be
blurred.
[0037] The antioxidant can be a phenol-based antioxidant,
phosphite-based antioxidant, or a mixture of these. The
phenol-based antioxidant can be 2,6-di-tert-butylphenol,
2,6-di-tert-butyl-4-methoxyphenol,
2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4-methoxyphenol,
2,4-dimethyl-6-tert-butylphenol, 2-tert-butylphenol,
3,6-di-tert-butylphenol, 2,4-di-tert-butylphenol,
2,6-di-tert-butyl-4-ethylphenol, 2-tert-butyl-4,6-methylphenol,
2,4,6-tert-butylphenol, 2,6-di-tert-butyl-4-stearylpronate phenol,
.alpha.-tocopherol, .beta.-tocopherol, .gamma.-tocopherol, naphthol
AS, naphthol AS-D, naphthol AS-BO,
4,4'-methylenebis(2,6-di-tert-butylphenol),
4,4'-methylenebis(6-tert-butyl-4-methylphenol),
2,2'-methylenebis(4-methyl-6-tert-butylphenol),
2,2'-methylenebis(4-ethyl-6-tert-butylphenol),
2,2'-ethylenebis(4,6-di-tert-butylphenol),
2,2'-propylenebis(4,6-di-tert-butylphenol),
2,2'-butanebis(4,6-di-tert-butylphenol),
2,2'-ethylenebis(6-tert-butyl-m-crezole),
4,4'-butanebis(6-tert-butyl-m-crezole),
2,2'-butanebis((6-tert-butyl-p-crezole),
2,2'-thiobis((6-tert-butylphenol),
4,4'-thiobis(6-tert-butyl-m-crezole),
4,4'-thiobis(6-tert-o-crezole),
2,2'-thiobis(4-methyl-6-tert-butylphenol),
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene,
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-amyl-4-hydroxybenzyl)benzene,
1,3,5-trimethyl-2,4,6-tris(3-tert-butyl-5-methyl-4-hydroxybenzyl)benzene,
2-tert-butyl-5-methyl-phenylaminephenol,
4,4'bisamino(2-tert-butyl-4-methylphenol), N-octadecyl-3-(3',5
'-di-tert-butyl-4'-hydroxyphenyl)propionate,
2,2,4-trimethyl-6-hydroxy-7-tert-butylchroman,
tetrakis(methylene-3(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)methane-
, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, or a
combination of these. However, the phenol-based antioxidant is not
limited thereto.
[0038] The phosphite-based antioxidant can be
tri(2,4-di-t-butylphenyl)phosphite,
bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,
bis(2,4-di-dicumylphenyl)pentaerythritol diphosphite,
tri(4-n-nonylphenyl)phosphite, or
tetrakis(2,4-di-tert-butyl-phenyl) 4,4'-biphenylene-diphosphite, or
a combination of these, but is not limited thereto.
[0039] The metal oxide included in the undercoat may include at
least one oxide selected from the group consisting of tin oxide,
indium oxide, zinc oxide, titan oxide, silicon oxide, zirconium
oxide, and aluminum oxide. In the present embodiment of the present
invention, the metal oxide can be a rutile-type titan oxide, and by
using about 0.01%-5% by weight of aluminum oxide titan oxide based
on the weight (100%) of titan oxide, electrostatic properties can
be improved and a printed smooth image can be obtained.
[0040] The binder included in the undercoat may include at least
one resin selected from a thermosetting resin obtained by thermally
polymerizing a oil-free alkyd resin, an amino resin, such as a
butylated melamine resin, a photosetting resin obtained by
polymerizing a polyurethane having an unsaturated bond or a resin
having an unsaturated bond, such as unsaturated polyester, a
polyamide resin, a polyurethane resin, an epoxy resin, or the
like.
[0041] In the organophotoreceptor, the thickness of the undercoat
may be in the range of about 0.1-20 .mu.m, and preferably about
0.2-10 .mu.m. When the thickness of the undercoat is less than 0.1
.mu.m, pores can be formed in the undercoat due to a high charge
voltage and black spots can be formed. On the other hand, when the
thickness of the undercoat is more than 20 .mu.m, it is difficult
to control electrostatic properties and an image quality may
decrease. In the undercoat, the weight ratio of the metal oxide and
the binder may be in the range of about 0.1:1-10:1. When the
relative amount of the binder is too high, the shielding
effectiveness of the metal oxide may decrease. On the other hand,
when the relative amount of the metal oxide is too high, the
organophotoreceptor is less adhesive to a photoreceptor drum.
[0042] In the organophotoreceptor, the charge generation layer can
be formed on the conductive support using a known method. A charge
generating material used to form the charge generation layer can be
an organic pigment, such as phthalocyanine-based pigment,
perylene-based pigment, indigo-based pigment, quinacridon-based
pigment, azo-based pigment, and preferably the phthalocyanine-based
pigment.
[0043] The charge generating material can be deposited or sputtered
to form a uniform layer. Alternatively, the pigment particles can
be dispersed in a binder, such as polyester resin, phenoxy resin,
or polyvinylbutyral resin, and then used to form a charge
generation layer having a thickness of about 0.1-2 .mu.m.
[0044] In the embodiment of the present invention, the
phthalocyanine-based pigment is used as the charge generating
material. The phthalocyanine-based pigment can be a
phthalocyanine-based derivative of Formula 1, a
phthalocyanine-based compound of Formula 2, or a mixture or
cocrystal thereof:
##STR00003##
[0045] where X.sub.1, X.sub.2, X.sub.3, and X.sub.4 are each
independently a substituted or unsubstituted 2,3-naphthalene ring
or a substituted or unsubstituted benzene ring, and at least one of
X.sub.1, X.sub.2, X.sub.3, and X.sub.4 is a 2,3-naphthalene
ring;
[0046] R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each
independently a hydrogen atom, a halogen atom, a nitro group, a
substituted or unsubstituted C1-20 alkyl group, or a substituted or
unsubstituted C1-C20 alkoxy group; and
[0047] M.sub.1 is a hydrogen molecule, a halogenated aluminum, or
Ti, V, Zr, Ge, Ga, Sn, Si, or In to which an oxygen atom, a halogen
atom, or hydroxyl group is bound; and
##STR00004##
where M.sub.2 is a hydrogen molecule, Cu, Fe, Mg, Sn, Pb, Zn, Co,
Ni, Mo, halogenized aluminum, or Ti, V, Zr, Ge, Ga, Sn, Si, or In
to which an oxygen atom, a halogen atom, or a hydroxyl group is
bound; and
[0048] R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10,
R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15, R.sub.16,
R.sub.17, R.sub.18, R.sub.19, and R.sub.20 are each independently a
hydrogen atom, a halogen atom, a nitro group, a substituted or
unsubstituted C1-20 alkyl group, or a substituted or unsubstituted
C1-20 alkoxy group.
[0049] The phthalocyanine compound used in the embodiment of the
present invention can be easily synthesized using a known method
(refer to F. H. Moser, A. L. Thomas "phthalocyanine compounds",
1963; PB85172.FIAT.FINAL REPORT 1313.Feb. 1, 1948; Japanese Patent
Laid-open Publication No. Hei 1-142658; and Japanese Patent
Laid-open Publication No. Hei 1-221461) which are hereby
incorporated by reference in their entirety.
[0050] When the phthalocyanine derivative of Formula 1 and the
phthalocyanine compound of Formula 2 are used to prepare the
phthalocyanine-based pigment used in the embodiment of the present
invention have the same central atoms, that is, Ml of Formula 1 is
identical to M.sub.2 of Formula 2, the phthalocyanine derivative of
Formula 1 and the phthalocyanine compound of Formula 2 can be
prepared at the same time.
[0051] As more benzene rings of the phthalocyanine structure of the
phthalocyanine derivative of Formula 1 are substituted, molecular
planes of the phthalocyanine derivative of Formula 1 and the
phthalocyanine compound of Formula 2 in the phthalocyanine-based
cocrystal are deposited in a more irregular direction. Therefore,
in order to obtain a cocrystal having a crystal form of high
sensitiveness, the number of a benzene ring substituted with a
2,3-naphthalene ring that is substituted or unsubstituted with a
halogen atom, a nitro group, an alkyl group, or alkoxy group of the
phthalocyanine structure of the phthalocyanine derivative of
Formula 1 may be three or less.
[0052] A method of preparing the phthalocyanine derivative of
Formula 1 will now be described in detail. First, a desired
substitute-containing dicarbonitril compound, such as
2,3-naphthalenedicarbonitril or 1,2-naphthalenedicarbonitril, is
transformed into a corresponding imine salt by using a metal
alkoxide so that the desired substitute-containing dicarbonitrile
compound can have higher reactivity than phthalonitrile. Then, the
corresponding imine salt is reacted with phthalonitrile, which is
used to synthesize a phthalocyanine compound, to selectively
synthesize a phthalocyanine derivative. Alternatively,
2,3-naphthalenedicarbonitril or 1,2-naphthalenedicarbonitril can be
reacted with phthalonitrile to synthesize a phthalocyanine
derivatives.
[0053] The first product obtained according to the method described
above can be a mixture of a phthalocyanine compound and a
phthalocyanine derivative in which benzene rings are substituted
with desired substitutes in a ratio of 1:99-99:1. The mixture ratio
may vary according to reaction conditions, such as a reaction
temperature, a mole ratio of reactants, a method of adding
reactants, or the like. The phthalocyanine derivative can be a
phthalocyanine derivative substituted with one, two, or three
substituents.
[0054] When the phthalocyanine-based pigment used in the embodiment
of the present invention is the phthalocyanine derivative of
Formula 1, it is not necessary to use a single kind of a
phthalocyanine derivative. That is, the phthalocyanine-based
pigment can be a mixture of at least two kinds of phthalocyanine
derivatives having different substitutes and/or different central
atoms.
[0055] An organic solvent used to synthesize the phthalocyanine
derivative of Formula 1 obtained as described above or the
phthalocyanine compound of Formula 2 may be an inert solvent having
a high boiling point, such as .alpha.-chloronaphthalene,
.beta.-chloronaphthalene, .alpha.-methyl naphthalene, methoxy
naphthalene, diphenyl naphthalene, ethylene glycol dialkyl ether,
quinoline, sulforane, dichlorobenzene, N-methyl-2-pyrrolidone, or
dichlorotoluene.
[0056] The phthalocyanine derivative of Formula 1 obtained as
described above or the phthalocyanine compound of Formula 2 may be
refined to increase its purity suitable for an electrophotographic
use. The refining method can be a cleaning method, a recrystalizing
method, an extraction method, a thermal suspension method, or a
sublimation method, using an acid, alkali, acetone, methyl alcohol,
ethyl alcohol, methyl ethyl ketone, tetrahydrofurane, pyridine,
quinoline, sulforane, .alpha.-chloronaphthalene, toluene, xylene,
dioxane, chloroform, dichloroethane, N,N-dimethylformamide,
N-methyl-2-pyrrolidone, or water. In addition to these refining
methods, other methods can be used to remove non-reacted products
or side reaction products within the scope of the present
invention.
[0057] When the phthalocyanine-based pigment is a mixture or a
cocrystal of the phthalocyanine derivative of Formula 1 and the
phthalocyanine compound of Formula 2, the weight ratio of the
phthalocyanine derivative of Formula 1 and the phthalocyanine
compound of Formula 2 may be about 1:1 or less, preferably about
0.0001:1-0.5:1, and more preferably about 0.0001:1-0.2:1, based on
the weight of the phthalocyanine compound of Formula 2.
[0058] In the present specification, a cocrystal refers to a state
in which at least two kinds of compounds are inserted in a
molecular state in a primary crystal particle. Whether crystalline
compounds are mixed in a form of a simple mixture or a cocrystal
can be easily identified using a known analysis method based on the
difference in properties. For example, such identification can be
obtained using new diffraction angles or new absorption peaks
appearing in an X-ray diffraction diagram, a ultraviolet light
absorption spectrum, or a visible light absorption spectrum which
are absent in the X-ray diffraction diagram, a ultraviolet light
absorption spectrum, or a visible light absorption spectrum of
initial (crude) compounds. Even when a simple mixture and a
cocrystal have the same diffraction angles and absorption peaks in
the same area, such identification can also be made. That is, even
in this case, since the cocrystal and the simple mixture have
different crystal forms or different growth rates, respective
initial (crude) compounds are treated in the same manner as the
process of preparing a cocrystal to produce a simple mixture which
has the same composition as the cocrystal, and then the
identification can be made from the difference in the diffraction
intensity or absorption intensity or the difference in respective
intensity ratios.
[0059] The cocrystal of the phthalocyanine derivative of Formula 1
and the phthalocyanine compound of Formula 2 is prepared by mixing
the phthalocyanine derivative of Formula 1 and the phthalocyanine
compound of Formula 2 in a molecular state according to a known
method. That is, the phthalocyanine derivative of Formula 1 and the
phthalocyanine compound of Formula 2 are dissolved into a molecular
state in a strong acid, such as a sulfuric acid. Then, the
resultant solution is added to a solvent, such as water or alcohol,
and then treated using a chemical method, such as an acid pasting
method that is used to precipitate cocrystal, or an acid slurry
method. Alternatively, by using a mechanical method using a
grinding or milling apparatus, the phthalocyanine derivative of
Formula 1 and the phthalocyanine compound of Formula 2 can be
treated together and physically combined into the same crystal. In
this mechanical method, the phthalocyanine derivative of Formula 1
and the phthalocyanine compound of Formula 2 may be completely
ground or milled until they become amorphous and then mixed.
[0060] It is important to uniformly mix the phthalocyanine
derivative of Formula 1 and phthalocyanine compound of Formula 2 to
make the phthalocyanine derivative of Formula 1 to effectively
function with the phthalocyanine compound of Formula 2. Such a
uniform composition can be obtained by using an additive used in
the dispersion process. The cocrystal prepared as described above
can be used as the charge generating material. However, when a
specific crystal form is desired, the obtained composition can be
post treated using a known method. In this case, a conversion
efficiency can be increased by performing the post treatment in
phthalocyanine compound crystal conversion conditions which are
used when a phthalocyanine derivative is not present or by adding
as a seed a compound having a crystal form desired as a crystal
conversion derivative.
[0061] When the phthalocyanine derivative of Formula 1 and the
phthalocyanine compound of Formula 2 which form the crystal mixture
are oxotitanyl phthalocyanines, the cocrystal may have the sharpest
diffraction peak at a Bragg angle (2.theta.+0.2.degree.) of
27.1.degree. in the X-ray diffraction spectrum, which is a crystal
form of .gamma.-type or Y-type oxotitanyl phthalocyanine, or have
the sharpest diffraction peak at a Bragg angle
(2.theta..+-.0.2.degree.) of 7.5.degree., which is a crystal form
of an .alpha.-type oxotitanyl phthalocyanine.
[0062] On the other hand, when the phthalocyanine derivative of
Formula 1 and the phthalocyanine compound of Formula 2 which form
the crystal mixture are nonmetallic phthalocyanines, the cocrystal
may have sharp diffraction peaks at Bragg angles
(2.theta..+-.0.2.degree.) of 7.5.degree. and 9.2.degree., which is
a crystal form of an X-type nonmetallic phthalocyanine.
[0063] The grinding or milling apparatus used in the selective post
treatment process to prepare a crystal mixture or obtain a crystal
form conversion, can be an attritor, a ball-mill, a sand-mill, a
high-speed mixer, a Branbury mixer, sback mixer, a roll-mill, a
3-roll mill, a nano mizer, a microfludizer, a stamp mill, a
planetary mill, vibration mill, a kneader and the like. When
required, a dispersion medium, such as a glass bead, a steel bead,
a zirconium oxide bead, an aluminum oxide ball, a zirconium oxide
ball, or flint can be used, during the milling. When required, a
grinding agent, such as a table salt, sodium carbonate, or sodium
sulfate, can be used during the grinding.
[0064] The organophotoreceptor according to an embodiment of the
present invention may have a multi-layered structure in which the
undercoat is deposited on the conductive support, and the charge
generation layer and the charge transport layer are sequentially
deposited to effectively generate and transport charge, or a
single-layered structure in which a charge generation and transport
layer is formed so that charges can be generated and transported in
the same layer.
[0065] In the multi-layer photoreceptor, the charge generation
layer is formed of the phthalocyanine-based pigment. The
phthalocyanine-based pigment, however, cannot form a film when used
alone. Accordingly, the phthalocyanine-based pigment is first
dispersed with an appropriate binder and a solvent using a
dispersing apparatus, and then the dispersion solution is coated on
the conductive substrate and dried to form the charge generation
layer. The amount of the phthalocyanine-based pigment contained in
the charge generation layer maybe in the range of about 10-100 wt
%, and preferably about 30-80 wt % based on the total weight of the
generation layer. The thickness of the charge generation layer may
be in the range of about 0.001-10 .mu.m, and preferably about
0.05-2 .mu.m. When thickness of the charge generation layer is less
than 0.001 .mu.m, it is difficult to obtain an uniform charge
generation layer and an image quality may deteriorate. On the other
hand, when the thickness of the charge generation layer is more
than 10 .mu.m, electrophotographic properties may decrease.
[0066] The charge transport layer is formed on the charge
generation layer. A charge transporting material can be both a hole
transporting material that transports holes and an electron
transporting material that transports electrons. When the
multi-layer photoreceptor is a negatively charged type, the charge
transporting material is the hole transporting material. When the
multi-layer photoreceptor is a positively charged type, the charge
transporting material primarily consists of the electron
transporting material. When the multi-layer photoreceptor has
positive and negative polarities, the hole transporting material
and the transporting material are used together for use. When the
charge transporting material has a film forming capability, the
charge transporting material itself can be used to form the charge
transport layer. However, in general, the charge transporting
material in a low molecular state does not have the film forming
capability, so that it is dissolved in a binder that has a film
forming capabilities and the resultant solution is coated on the
charge generation layer and dried to form the charge transport
layer. The thickness of the charge transport layer may vary
according to the application, and can be in the range of about 5-50
.mu.m.
[0067] In the single-layer photoreceptor, the charge generation and
transport layer can be formed by dispersing the
phthalocyanine-based pigment and a known binder with a solvent,
coating the dispersed product on the conductive substrate, and then
drying the coated product. In the preparation process, there is no
need to additionally use a charge transporting material because the
phthalocyanine pigment itself is a photoconductive material and has
a charge transporting capability. In the charge generation and
transport layer, the amount of the phthalocyanine-based pigment may
be in the range of about 1-40 wt %. However, a known charge
transporting material can be used together in order to increase
plasticity of a film and a charge transporting efficiency. When the
charge transporting material is additionally used, the amount of
phthalocyanine-based pigment contained in the charge generation and
transport layer may be in the range of about 0.1-50 wt %, and
preferably about 0.2-10 wt %, and the amount of the resin may be in
the range of 20-70 wt %.
[0068] The charge transporting material can be a hole transporting
material, an electron transporting material, or a mixture of these,
and preferably the mixture of the hole transporting material and
the electron transporting material. In the mixture of the hole
transporting material and the electron transporting material, the
ratio of the hole transporting material and the electron
transporting material may vary according to polarity or mobility of
charges. The thickness of the charge generation and transportation
layer may be in the range of about 5-50 .mu.m.
[0069] As the transporting material used in the embodiment of the
present invention, the hole transporting material can be a known
hole transporting material, such as hydrazone-based compound,
pyrazoline-based compound, oxadiazole compound, styryl compound,
arylamine compound, oxazole-based compound, pyrazoline-based
compound, pyrazolone-based compound, stylbene compound, polyaryl
alkane-based compound, polyvinylcarbazole-based compound and a
derivative thereof, N-acrylamidmethylcarbazole polymer, quinoxaline
polymer, vinyl polymer, triphenylmethane polymer, stylene
copolymer, polyacenaphthen, polyindene, a copolymer of
acenaphthylene and stylene, or formaldehyde-based condensed
resin..
[0070] The electron transporting material can be a known electron
transporting material, such as benzoquinone-based compound,
naphthoquinone-based compound, anthraquinone-based compound,
malononitrile-based compound, fluorenone-based compound,
dicyanofluorenone-based compound, benzoquinoneimine-based compound,
diphenoquinone-based compound, stylben quinone-based compound,
diiminonquinone-based compound, dioxotetracendion compound, or a
sulfurized pyrane-based compound. Meanwhile, the charge
transporting material used in the embodiment of the present
invention is not limited to the hole transporting material or
electron transporting material, and can be any transporting
material having the mobility of 10.sup.-8 cm.sup.2/s or more. In
some cases, at least two kinds of the charge transporting material
can be used together.
[0071] In the electrophotographic photoreceptor according to an
embodiment of the present invention, the charge generation layer,
the charge transport layer, or the charge generation and
transportation layer can be prepared using a second binder. The
second binder can be a conductive resin having a film forming
capability, such as polyvinylbutylral, polyacrylate (a condensed
polymer of bisphenol A and phthalic acid, polycarbonate, polyester,
phenoxy resin, polyacetic acid vinyl, acryl resin, polyacryl amide
resin, polyamide, polyvinyl pyridine, cellulose-based resin,
urethane resin, epoxy resin, silicon resin, polystyrene,
polyketone, polyvinyl chloride, vinyl chloride-vinylic acid
copolymer, polyvinylacetal, polyacrylonitrile, phenol resin,
melamine resin, casein, polyvinyl alcohol, or polyvinyl
pyrrolidone, or an organic photoconductive resin, such as poly
N-vinylcarbazole, polyvinyl anthracene, or polyvinylpyrene.
[0072] The second binder used to prepare the charge transport layer
may include the compound of Formula 3, such as PANLIGHT TS2050,
PANLIGHT TS2040, or PANLIGHT TS2030, and/or the compound of Formula
4, such as TOUGHZET B-200, TOUGHZET B-300, or TOUGHZET B-500.
##STR00005##
[0073] The second binder can be a polycarbonate binder resin or a
mixture of at least two kinds of polycarbonates having different
molecular weights. In some cases, the second binder can be a
mixture of the compound of Formula 3 (PCZ) and the compound of
Formula 4 (BPPC).
[0074] In the process of preparing the charge generation layer, the
charge transport layer or the charge generation and transportation
layer of the electrophotographic photoreceptor according to an
embodiment of the present invention, the solvent of the coating
solution may vary according to the used resin. The selected solvent
may not affect an adjacent layer during the coating. The solvent
may be selected from aromatic hydrocarbons, such as benzene,
xylene, ligroin, monochlorobenzene, or dichlorobenzene; ketones,
such as acetone, methylethylketone, or cyclohexanone; alcohols,
such as methanol, ethanol, or isopropanol; esters, such as acetic
acid ethyl, or methyl cellosolve; aliphatic halogenized
hydrocarbons, such as carbon tetrachloride, chloroform,
dichloromethane, dichloroethane, or trichloroethylene; ethers, such
as tetrahydrofurane, dioxane, dioxolane, or ethylene glycol
monomethyl ether; amides, such as N,N-dimethyl formamid, or
N,N-dimethyl acetamid; and sulfoxides, such as dimethylsulfoxide.
In the process of preparing the charge generation layer or the
charge generation and transportation layer used in the embodiment
of the present invention, a known charge generating material or a
salt/pigment used to control spectroscopic sensitiveness can be
used together with the phthalocyanine-based pigment. The charge
generating material or a salt/pigrnent used to control
spectroscopic sensitiveness can be bisazo-based compound,
triazo-based compound, anthraquinone-based compound, perylene-based
compound, perynone-based compound, azulenium salt-based compound,
scuarium salt-based compound, polycyclo quinone, pyrolopyrrol
compound, or phthalocyanine, such as naphthalocyanine.
[0075] Furthermore, in the process of preparing a photoreceptor
using the phthalocyanine-based pigment, an electron receiving
material may be further added to improve sensitiveness, to decrease
the remaining charge potential, or to decrease a fatigue occurring
when repeatedly used. The electron receiving material can be a
compound having high electron affinity, such as anhydrous succinic
acid, anhydrous maleic acid, dibrom anhydrous succinic acid,
anhydrous phthalic acid, 3-nitro anhydrous phthalic acid, 4-nitro
anhydrous phthalic acid, anhydrous pyromellitic acid, pyromellitic
acid, trimellitic acid, anhydrous trimellitic acid, phthalimid,
4-nitrophthalimid, tetracyanoethylene, tetracyanoquinodimethane,
chloranyl, bromanyl, o-nitro benzoic acid, or p-nitro benzoic
acid.
[0076] The amount of the electron receiving material may be in the
range of about 0.01-100 wt % based on the total weight ofthe charge
generating material. In addition, the photoreceptor may further
include a deterioration preventing agent, such as an antioxidant or
a light stabilizer, to improve the resistance to the environment
and improve the stability with respect to harmful light. The
deterioration preventing agent can be a chromanol derivative, such
as tocopherol, an etherfied compound of the chromanol derivative,
an esterified compound of the chromanol derivative, polyaryl alkane
compound, hydroquinone derivative, mono and dietherified compounds
of the hydroquinone derivative, benzophenone derivative,
benzotriazole derivative, ether sulfide compound, phenylenediamine
derivative, phosphonic acid ester, phosphorous acid ester, phenol
compound, phenol compound having a steric hindrance, linear amine
compound, ring amine compound, or an amine compound having a steric
hindrance. The antioxidant may be the same as in the undercoat.
[0077] An electrophotographic imaging apparatus including the
organophotoreceptor according to an embodiment of the present
invention, an electrophotographic drum including the
organophotoreceptor according to an embodiment of the present
invention, an electrophotographic cartridge including the
organophotoreceptor according to an embodiment of the present
invention will now be described in detail. First, the
electrophotographic imaging apparatus will be described.
[0078] FIG. 1 is a schematic view of an electrophotographic imaging
apparatus 30 including an electrophotographic drum 28 and an
electrophotographic cartridge 21, according to an embodiment of the
present invention. The electrophotographic cartridge 21 includes an
organophotoreceptor 29, at least one charging device 25 that
charges the organophotoreceptor 29, a developing device 24 that
develops an electrostatic latent image formed on the
organophotoreceptor 29, and a cleaning device 26 that cleans the
surface of the organophotoreceptor 29. The electrophotographic
cartridge 21 can be installed in the electrophotographic imaging
apparatus 30 and separated from the electrophotographic imaging
apparatus 30.
[0079] In the electrophotographic imaging apparatus 30, the
organophotoreceptor 29 is located on the electrophotographic drum
28, and the organophotoreceptor 29 and the electrophotographic drum
28 can be installed in the electrophotographic imaging apparatus 30
and separated from the electrophotographic imaging apparatus
30.
[0080] In general, the electrophotographic imaging apparatus 30
includes a photoreceptor unit including the organophotoreceptor
drum 28 and the electrophotographic drum 29; the charging device 25
that charges the photoreceptor unit; an imagewise light irradiation
device 22 that irradiates an imagewise light to a photoreceptor
unit charged by the charging device in order to form a
electrostatic latent image on the photoreceptor unit; the
developing unit 24 that develops the elastic latent image using a
toner in order to form a toner image on the photoreceptor unit; and
a transferring device 27 that transfers the toner image onto a
receptor, such as paper P. The photoreceptor unit includes the
organophotoreceptor 29 which will be described in detail. The
charging device 25 is included in a charging unit, and can be
provided with voltage and charge the organophotoreceptor 29 by
contacting the organophotoreceptor 29. The electrophotographic
imaging apparatus 30 may further include a pre-exposure unit 23
that removes the latent charge at the surface of the
organophotoreceptor 29 in order to prepare a next cycle.
[0081] The organophotoreceptor according to an embodiment of the
present invention can be used in an electrophotographic imaging
apparatus, such as a laser printer, a copier, or a facsimile.
[0082] The present invention will be described in further detail
with reference to the following examples. These examples are for
illustrative purposes only and are not intended to limit the scope
of the present invention. In Preparation Examples and Examples,
`parts` and `%` denote parts by weight and % by weight,
respectively.
PREPARATION EXAMPLE 1
[0083] 800 parts of methanol was added to 20 parts (0.112 mole) of
2,3-naphthalene dicarbonitrile and then 36.38 parts (0.168 mole) of
sodium methoxide was added thereto in a nitrogen atmosphere in a
flask installed with a refluxing device. The resultant solution was
reacted at a temperature of 60-80.degree. C. for 1-3 hours. The
reaction product was cooled to 0.degree. C..quadrature. or lower so
that a yellow product was formed. The yellow product was filtered,
washed using a cooled methanol, and then dried at 40.degree. C. for
10 hours in a vacuum oven. As a result, an imine derivative of the
2,3-naphthalene dicarbonitrile was obtained. 27.3 parts (0.213
mole) of phthalonitrile and 16.48 parts (0.071 mole) of the imine
derivative of the 2,3-naphthalene dicarbonitrile prepared as
described above were added to 450 parts of
.alpha.-chloronaphthalene and then 14.84 parts (0.078 mole) of
titan tetrachloride was dropwise added thereto in a nitrogen
atmosphere in a flask installed with a refluxing device. Then, the
resultant mixture was reacted at 200-220.degree. C. for 4 hours
while being mixed. Then, the reaction product was filtered at
100-130.degree. C., and the filtered pigment was sequentially
washed using .alpha.-chloronaphthalene, methanol, and water. The
washed pigment was dispersed in 1000 parts of 5% ammonia water, and
then heated and mixed at 90.degree. C. for 2 hours. The resultant
solution was filtered and dried at 40.degree. C. in a vacuum oven
for 10 hours. As a result, 16.95 parts of a mixture of oxotitanyl
phthalocyanine and a derivative of the oxotitanyl phthalocyanine in
which a benzene ring is substituted with a naphthalene ring.
[0084] The mixture of oxotitanyl phthalocyanine and the oxotitanyl
phthalocyanine derivative was analyzed using a mass spectrometer.
As a result, it was found from the intensity ratio that an
oxotitanyl phthalocyanine derivative in which one of the benzene
rings of the oxotitanyl phthalocyanine is substituted with
2,3-naphthalene was 40%.
PREPARATION EXAMPLE 2
[0085] 10 parts of the mixture obtained according to Preparation
Example 1 was mixed and dissolved in 200 parts of 98% sulfuric acid
at a temperature of 0.quadrature. or lower. The resultant sulfuric
acid solution was added to 2000 parts of water at 0.quadrature. or
lower while being stirred to reprecipitate a cocrystal of the
oxotitanyl phthalocyanine and the oxotitanyl phthalocyanine
derivative. The precipitated cocrystal was filtered and washed
until the filtering solution became neutral. 200 parts of
dichlorobenzene was added to the wet cocrystal of the oxotitanyl
phthalocyanine and the oxotitanyl phthalocyanine derivative and
then treated using zirconium oxide balls having a diameter of 5 mm
and a ball mill for 78 hours. The dispersed solution was added to a
great amount of acetone so that the cocrystal aggregated. The
aggregated cocrystal was filtered, washed, and then dried in a
vacuum oven at 40.quadrature.. An X-ray diffraction (XRD) of the
obtained product was measured. The results are shown in FIG. 2.
[0086] 5 parts of the dried cocrystal, 2.5 parts of
polyvinylbutyral resin (BM2: Sekisui Kagaku Kogyo), and 80 parts of
tetrahydrofurane were dispersed using an alkali glass bead having a
diameter of 1-1.5 mm and a paint shaker for 30 minutes. Such
dispersion process was repeated four times. Then, 272 parts of
tetrahydrofurane was added to the dispersed product to prepare a
coating solution for a charge generation layer.
PREPARATION EXAMPLE 3
[0087] A coating solution for a charge generation layer was
prepared in the same manner as in Preparation Example 2, except
that 9.5 parts of oxotitanyl phthalocyanine and 0.5 parts of the
mixture of the oxotitanyl phthalocyanine and the oxotitanyl
phthalocyanine derivative prepared according to Preparation Example
1 were used instead of 10 parts of the mixture of the oxotitanyl
phthalocyanine and the oxotitanyl phthalocyanine derivative. The
XRD of the mixture of the oxotitanyl phthalocyanine and the
phthalocyanine derivative was measured. The results are shown in
FIG. 3.
PREPARATION EXAMPLE 4
[0088] 9.5 parts of oxotitanyl phthalocyanine and 0.5 parts of the
mixture of the oxotitanyl phthalocyanine and the oxotitanyl
phthalocyanine derivative prepared according to Preparation Example
1 were used instead of 10 parts of the mixture of the oxotitanyl
phthalocyanine and the oxotitanyl phthalocyanine derivative used in
Preparation Example 2, and a crystal form was obtained using the
method according to Comparative Preparation Example 2. The XRD of
the dried cocrystal was measured. The results are shown in FIG. 4.
5 parts of the dried cocrystal, 2.5 parts of polyvinylbutylal resin
(BM2: Sekisui Kagaku Kogyo), and 80 parts of tetrahydrofurane were
dispersed using an alkali glass bead having a diameter of 1-1.5 mm
and a paint shaker for 30 minutes. Such dispersion process was
repeated four times. Then, 272 parts of tetrahydrofurane was added
to the dispersed product to prepare a coating solution for a charge
generation layer.
COMPARATIVE PREPARATION EXAMPLE 1
[0089] An oxotitanyl phthalocyanine was prepared in the same manner
as in Preparation Example 1, except that 0.071 mole of
phthalonitrile was used instead of 0.071 mole of the imine
derivative of 2,3-naphthalenedicarbonitril. Then, the same
experiment as Preparation Example 2 was carried out to prepare a
coating solution for a charge generation layer.
COMPARATIVE PREPARATION EXAMPLE 2
[0090] Alpha-type titanyl phthalocyanine was prepared according to
the method disclosed in U.S. Pat. No. 4,728,592. 5 parts of
alpha-type titanyl phthalocyanine, 2.5 parts of polyvinylbutylal
resin (BM2: Sekisui Kagaku Kogyo), and 80 parts of tetrahydrofurane
were dispersed using an alkali glass bead having a diameter of
1-1.5 mm and a paint shaker for 30 minutes. Such dispersion process
was repeated four times. Then, 272 parts of tetrahydrofurane was
added to the dispersed product to prepare a coating solution for a
charge generation layer.
EXAMPLE 1
[0091] 80 parts by weight of nylon resin (CM8000 produced by Toray
Co.) was dissolved in 320 parts by weight of an organic solvent
(methanol/propanol=1/1 wt %) and then 4000 parts by weight of 5
mm.PHI. alumina ball, 160 parts by weight of titan oxide (TTO-55N
produced by Ishihara Co.), and 4 parts by weight of antioxidant
2,6-di-tert-butyl-4-methylphenol were added thereto and dispersed
using a ball mill for 20 hours. The dispersion solution was diluted
using 1120 parts by weight of an organic solvent to prepare a
coating solution for an undercoat.
[0092] The coating solution for an undercoat was coated on an
aluminum drum to a thickness of 1-5 .mu.m and dried at 60.degree.
C. in an oven for 30 minutes to form an undercoat. The coating
solution for a charge generation layer prepared according to
Preparation Example 3 was coated on the undercoat to a thickness of
0.2 .mu.m and dried to form a charge generation layer. Then, a
coating solution for a charge transport layer prepared by
dissolving 4.2 parts of 4-dibenzylamino-2-methyl benzaldehyde
diphenyl hydrazone(CTC191 produced by Takasago Co.), 4.2 parts of
1,1-bis-(para-diethyl aminophenyl)-4,4-diphenyl-1,3-butadiene(T405
produced by Takasago Co.), 10.5 parts of polycarbonate resin (B500
produced by Idemitz), 1 part of an antioxidant (IrganoX 565
produced by Ciba-Geigy Co.), and 1 part of antioxidant
tris(2-t-butyl-4-methylphenyl)phosphite in 70 parts of
tetrahydrofurane and 8.6 parts of xylene was coated on the dried
charge transport layer to form a charge transport layer having a
thickness of 20 .mu.m and then dried. As a result, a negative
charge multi-layer photoreceptor was manufactured. The
electrostatic properties of the organophotoreceptor were measured
using an electrostatic property measuring device (QEA-2000) and an
optical fatigue thereof was measured.
EXAMPLE 2
[0093] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for the charge
transport layer was prepared using 8.4 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine instead of 4.2
parts of 4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone
(CTC191 produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
EXAMPLE 3
[0094] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for the charge
transport layer was prepared using 4.2 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine and 4.2 parts by
weight of N,N,N',N'-tetrakis(4-methylphenyl)benzidine instead of
4.2 parts of
4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone(CTC191
produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
EXAMPLE 4
[0095] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for the charge
transport layer was prepared using 4.2 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine and 4.2 parts by
weight of 4-methoxyphenyldiphenylamine instead of 4.2 parts of
4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone(CTC191
produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
COMPARATIVE EXAMPLE 1
[0096] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 1 was used.
COMPARATIVE EXAMPLE 2
[0097] This experiment was carried out in the same manner as in
Example 1, except that an aluminum drum that was treated with
alumite was used instead of the undercoat.
EXAMPLE 5
[0098] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 4 was used.
EXAMPLE 6
[0099] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 4 was used, and the
coating solution for a charge transport layer was prepared using
8.4 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine instead of 44.2
parts of 4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone
(CTC191 produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
EXAMPLE 7
[0100] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 4 was used, and the
coating solution for a charge transport layer was prepared using
4.2 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine, and 4.2 parts
by weight of N,N,N',N'-tetrakis(4-methylphenyl)benzidine instead of
44.2 parts of 4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone
(CTC191 produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
EXAMPLE 8
[0101] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 4 was used, and the
coating solution for a charge transport layer was prepared using
4.2 parts by weight of
N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)benzidine and 4.2 parts by
weight of 4-methoxyphenyldiphenylamine instead of 44.2 parts of
4-dibenzylamino-2-methylbenzaldehydediphenylhydrazone (CTC191
produced by Takasago Co.) and 4.2 parts of
1,1-bis-(para-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene (T405
produced by Takasago Co.).
COMPARATIVE EXAMPLE 3
[0102] This experiment was carried out in the same manner as in
Example 1, except that the coating solution for a charge generation
layer prepared according to Preparation Example 2 was used.
COMPARATIVE EXAMPLE 4
[0103] This experiment was carried out in the same manner as in
Example 1, except that an aluminum drum that was treated with
alumite was used instead of the undercoat, and the coating solution
for a charge generation layer prepared according to Preparation
Example 2 was used.
[0104] Properties of the photoreceptors prepared according to
Examples 1-8 and Comparative Examples 1-4 were measured. The
results are shown in Table 1. Methods of measuring properties of
photoreceptors and definition of marks are described.
TABLE-US-00001 TABLE 1 Section Initial After 2000 cycles Properties
E.sub.1/2 E.sub.100 V.sub.r E.sub.1/2 E.sub.100 V.sub.r Example 1
0.16 0.45 8.5 0.15 0.42 25.4 Example 2 0.15 0.52 11.4 0.13 0.48
38.2 Example 3 0.14 0.42 10.2 0.13 0.32 30.7 Example 4 0.14 0.40
9.8 0.14 0.35 32.5 Example 5 0.37 0.83 6.6 0.35 0.79 28.4 Example 6
0.35 0.82 7.0 0.32 0.75 34.5 Example 7 0.33 0.78 10.0 0.32 0.74
32.2 Example 8 0.34 0.80 9.5 0.33 0.78 31.0 Comparative 0.16 0.46
8.0 0.13 0.32 45.3 Example 1 Comparative 0.15 0.42 8.2 0.14 0.40
34.2 Example 2 Comparative 0.36 0.82 7.0 0.34 0.75 40.3 Example 3
Comparative 0.35 0.80 6.2 0.35 0.78 36.4 Example 4 Note)
E.sub.1/2(.mu.J/cm.sup.2): Exposure energy required until the
initial charge potential (V.sub.0) drops to V.sub.0/2;
E.sub.100(.mu.J/cm.sup.2): Exposure energy required until the
initial charge potential (V.sub.0) drops to -100 V; and
V.sub.r(-V): Latent potential after 10-second light irradiation
after charged
[0105] As a result of measuring a photo fatigue, it was found that
E.sub.1/2 and E.sub.100 sensitiveness were stable and the increase
of the latent potential was suppressed.
[0106] As described above, an organophotoreceptor according to the
present invention provides a stable image quality obtained by
uniform coating with a coating solution for a charge generation
layer having high dispersion stability and high storage stability
and excellent electrical properties. Accordingly, the
organophotoreceptor is very useful for preparation of an
electrophotographic photoreceptor having excellent electrical
properties and image properties. An electrophotographic
photoreceptor according to the present invention has high
sensitiveness to a long wavelength of about 780 nm so that the
electrophotographic photoreceptor can be used in a laser printer, a
copier, a facsimile, or a multifunction apparatus, all of which
uses light of such a long wavelength.
[0107] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *